Lightfastness Explained

Here we will be discussing a very important topic that can leave a lot of artists confused, whether amateur or professional.

I feel it is important to know about what lightfastness actually is irrespective of where you are in your art career or if you just do art as a hobby like most people. It is less relevant if you only do art as a hobby, but I still think it’s beneficial in the long run especially if you create a piece of art you like and want to keep for yourself.

What is lightfastness?

Let’s first delve in to what lightfastness actually is and the potential consequences of not understanding the principles behind it.

Lightfastness is simply how the pigment of the art materials you are using interact with light itself and it is a measurement of a pigment’s ability to resist fading or discolouration under normal circumstances. This can be any type of sunlight or ultraviolet light.

So how will this affect you as the artist?

I’ll use my expertise on coloured pencils and paints to explain however please be aware that lightfastness is universal and represents all coloured mediums including paints, pens, pastels, inks etc (especially inks in printers if you wish to produce giclée prints which will last).

Let’s say for example you’re an amateur artist on a budget, not many artists or people have the luxury of being able to afford the best paper, the best pencils, the best equipment. It’s simply not possible at times and the best art materials do cost substantially more than the lesser known options, however the more expensive art materials are worth it and lightfastness is major proof of this.

I would always say that the general rule of thumb is that if an art product is costlier, then 9 times out of ten it will be of a superior quality to something that’s much cheaper in comparison. To demonstrate lightfastness can be difficult due to the timeframe of how a pigment/pigments react to surrounding light and how the pigment themselves eventually fade away. Some pigments can fade in weeks if they are extremely poor and other poor ones can even take up to a year. The length of exposure, and strength of the light also affect how fast fading can occur.

Considering lightfastness as a professional artist

As an example let’s use a simple explanation. Let’s say you are a professional artist and a client asks you to paint them a minimalist piece, such as a red square. A simple red square either on a piece of paper or canvas that they can hang on their wall to look at everyday.

The professional artist in this example would look for paints that are lightfast, the client is paying money for a service and the artist has to respect that. Purchasing paint that is “lightfast” is the only viable option as it means the red square you paint will not fade over time and will even outlast you if you buy the best options. The client is happy and you don’t get a disgruntled owner many months or years later emailing you and asking why their beautiful red square is getting fainter and fainter as the days go by.

This video demonstrates the different in lightfastness between two similar colours in the Winsor & Newton Professional Watercolour range.

Considering lightfastness as a hobby artist

Now let’s say you’re a hobby artist, purchasing cheaper art supplies isn’t a bad thing in this instance. Let’s say you want to paint yourself a red square. Ultimately the red square you paint won’t be much different than the red square the professional artist did with the best paints but it will fade much much faster and will be of lesser quality.

Now imagine that’s a piece of work you’ve done that you’re really proud of, something more complex than a red square and you hang it up on the wall facing a window to showcase your skills. Through that window the sunlight shines through on a daily basis and while it’s doing that, imagine that the light is physically assaulting your artwork. Think of it like a body of water eroding a wall of rock, eventually the rock recedes and crumbles due to the bombardment and energy displaced by the water striking it on a daily basis, and light is the same albeit to a less dramatic and obvious effect. The light is eating away at the pigmentation and while the pigment may put up a fight, the light will eventually win the battle and break the pigment down, hence the weakening of the colour and vibrancy.

Now the expensive art materials with much higher quality pigments fare differently. Imagine the pigments having an invisible wall right in front of them for protection, light can attack it as much as it wants but the effects are negligible. So much so that the difference between terrible pigments and outstanding pigments is vast. The worst quality pigments in a bright environment can last between 4 months and a year in comparison to the best pigments which can remain as colourful as the day you applied them for over 100 years in what can be called” museum conditions“.

Now let’s be honest, no colour can last forever and one day the barrier will be broken, but you will be long gone to care about that or to rectify anything anyway. Nothing lasts forever in the art world unless preserved in museums with the highest standards of quality control.

Considering lightfastness when selling prints

One thing that is also worth noting here is that lightastness is less of a consideration if you are planning on reproducing your work to sell prints. For example, if you are just making prints to sell, you can store your original away from the light, and therefore lightfastness will be less important to you.

This is often what people do when they use a dye based ink/pen to produce an artwork, as dyes are not lightfast at all. 

Understanding which products are lightfast

The question I hear you all asking now is “How on Earth do I differentiate between what is lightfast and what isn’t lightfast?” How do I know if the pencils/pens/paints/inks I’m using are even lightfast or not?

Luckily there is an answer to this problem, and it’s much easier to understand and relate to than you may think.
Using coloured pencils as an example, cheap pencil manufacturers have little or next to no information on their websites or the pencils themselves regarding lightfastness. Children’s pencils being the key point such as Crayola. There are people who purchase Crayola pencils to do commissions for people which I always advise against, to reiterate the point made previously, you’re going to have angry customers lining up to get you and it will also be a poor reflection on you as the artist when the work fades away (this may take a year, may even take 5 years depending on where they place it…it’s still a problem however).

You can expect most artists/professional quality art materials to have a decent light fastness rating, apart from some pigments which are naturally less lightfast, and the lightfastness rating information for each colour available either on the product itself, or on a colour chart or website.

Lightfastness rating on various acrylic paints, vary from brand to brand.

Lightfast scales and ratings in pencils

For most Artists’ pencils on the market, lightfastness information is readily available on the pencil manufacturers/suppliers respective websites in the forms of charts and other information. Depending on what pencil brand you use, different companies use different scales to represent how lightfast their pencils are, or if they are lightfast at all.

The two main scales to measure lightfastness are the blue wool scale and the ASTM scale (American Standard Test Measure). The blue wool scale operates from numbers 1-8, 1 being extremely poor lightfastness and 8 being the absolute maximum lightfastness possible.

The Blue Wool Scale being used to test Winsor & Newton paint in their sunlight machine.

Anything that is a 6 or above is considered acceptable for professional artists who do commissions for clients or people who want their work to be preserved for the maximum period of time.

The ASTM operates using a Roman Numeral system and goes from I to VI. I is the highest form of lightfastness and would equate to an 8 on the Blue wool scale and a VI would equate to a 1 on the blue wool scale. The confusion can lie in the difference of scales, one using a higher number to represent the best lightfastness and one using a lower number to represent the best lightfastness.

Lightfastness chart from Wikipedia shows suggestive relations of the lightfastness ratings on different measure scales and the relation relative to time in direct sunlight and normal conditions of display: away from a window, under indirect sunlight and properly framed behind a UV protective glass.

Some manufacturers also have their own unique system which can further add to the confusion of it all as at times you don’t know which system is being used or whether a lower rating equals a greater product vs a higher one and vice versa but all manufacturers will use the blue wool scale or ASTM scale in some way and then incorporate that into their own system.

If you are looking for a pencil that has the best lightfastness then you want to look for the manufacturers rating that represents ‘Excellent Lightfastness’ either shown on the barrel of the pencil or displayed on the website detailed next to the pigment it represents.

Caran d’Ache Supracolor soft watercolour pencils are rated from * (good) to *** (excellent) based on the blue wool scale.

Pencil brands offering supreme lightfast rating

As of typing this, there are currently only 2 pencil manufacturers that offer a specific range of pencils that have a supreme lightfast rating. Each range offers 100 different coloured pencils, so that’s 200 completely lightfast pencils if you’re able to afford to purchase both ranges. This means that all the pencils in the respective ranges are extremely lightfast and the best of what you can get by today’s standards.

Caran d’Ache Luminance

The first manufacturer is Caran d’Ache with the Luminance coloured pencils range. This was the first ever pencil set to be released that offered incredible lightfastness properties and a wide range of colours for professional artists to use. The pencils in this range vary from 100% lightfastness to 80% lightfastness. 80% and above is absolutely perfect for anyone wanting their work to be of the best quality and done with the upmost of care regarding lightfastness. Any pencil you pick up is essentially safe to use in regards to colour and the pencils themselves are truly beautiful to use.

I also want to stress that not even all the Caran d’Ache ranges use stars, the Museum range uses stars, the Luminance range just have LFI and LFII.

Luminance pencil with a LFI rating – the best lightfastness

It’s recommend that you always refer to the key when looking at a colour chart to see what lightfastness rating is being used. You can download colour charts which have a key, or the Ken Bromley Art Supplies catalogue always has a key for every colour chart which has a lightfastness rating, and the website displays the information when you click on the ‘i’  symbol on the colour chart.  Below are three examples of the colour information keys displayed in our catalogue.

Daniel Smith Watercolours
Michael Harding Oils
Schmincke Watercolours

Below is a selection of pencils from the Polychromos, Lightfast, Luminance and Museum ranges. Most of the other pencil ranges don’t show a lightfastness rating on the pencils themselves. 

Derwent Lightfast

The next range is the Derwent Lightfast range, the clue being in the title. Derwent use the ASTM scale for the Lightfast range of pencils and on the barrel it will either display a LF1 or LF2 label, LF1 being 100% lightfast and LF2 being 80% lightfast.

If you are a coloured pencil artist like myself you can fully use the Lightfast and Luminance range together as long as you are aware that the Luminance are a wax based pencil in comparison to the Lightfast being an oil based pencil.

Please be aware however as discussed before, due to the quality of pigments used, the manufacturing process and the overall high standards of such companies that want to give peoples and artists the best products possible, the price gap between cheap pencils and these pencils can be severe especially if you are buying in bulk. The price difference however in my opinion is justified considering the Lightfast range were specifically tested in Arizona under the gaze of the burning sun to test just how strong the pigments were against it.

Lightfast ratings in other mediums

Moving away from pencils, other art materials and paints in particular offer lightfast ratings on their products which again utilise the scales mentioned. A company that manufactures both pencils and paints would use the same systems across all their products, for example if a pencil had a star rated system on the barrel then this would also be applicable to the paints too using the same star system. If there is no indication to lightfastness proprieties on any packaging or on the art materials themselves it’s highly likely they aren’t lightfast at all, but if you are using the highest quality brands then there will always be lightfast information available in some form.

Schmincke which is a German brand create some of the most beautiful watercolour pans and vibrant colours. This is a company that also uses a star system however the star rating on these go from 1-5, 5 stars being the best and 1 being the worst. Again we can see where a lot of confusion lies when you start to build up a collection of art materials and each product you have offers different information, different ratings and different scales but ultimately they all relate to the same thing. I think it would be much simpler to just have one universal system and integrate that into art supplies with a star system like it is now however it needs to be more constant.

Instead of one brand having 3 stars as a maximum, one brand having 5 stars and other brands having their own systems, let’s make it all the same so that no matter which art material you use then you know the system and how it works and are more confident to trust the materials you are using.

Finally, I also want to point out that some paint ranges refer to lightfastness as ‘permanence’. E.g, the Winsor & Newton Professional quality watercolours have a permanence and an ASTM rating, their Designers Gouache range just has a permanence rating.  The permanence rating not only takes into account the lightfastness, but also the chemical stability of the colour.

Different lightfast ratings on watercolour paint, Schmincke Horadam, Daniel Smith, White Nights, Cotman, W&N Professional and Rembrandt.

Things you can do if you can’t afford lightfast

What if however you can’t afford the expensive pencils and paints that offer the highest lightfast rating? Is there anything you can do to defy the process of how light interacts with pigments and protect your work even if you use cheaper materials.

In most instances yes there are a few things you can do. Again I will state that if you are a professional artist wanting to make a living from your art it’s important that you use the highest quality products available at your disposal but if you are wanting to create a drawing for a friend or a piece of art for a loved one that they can hang up you can do the following:

  1. Advise that they hang up the art away from sunlight or any UV light. If it’s near an open window or somewhere light can “attack” it then the pigments will eventually be broken down over time. Having the art on a wall facing away from the sun or in a corner will allow it to last much longer than if it were in direct sunlight.
  2. Have your art framed in UV glass, or use a UV varnish. This can be a costly but highly suitable option. Once framed the UV glass filters out all the UV rays before they can reach the artwork acting like a barrier which in turn protects it. Depending on who you use to frame your work it is much more expensive than a standard frame but it is a fantastic option.
    UV varnish can be used on oil and acrylic paintings for extra protection against fading.
    Combining points 1 and 2 is an even better solution. This is an option I give to clients of my own work, framing a drawing with UV glass adds more protection on top of the already lightfast qualities of the pigments. More protection can never be a bad thing.
  3. Don’t hang up the art at all. I have seen numerous examples of art done with cheaper materials where the art is still looking good after 8 years because it’s been placed in a drawer or in storage somewhere. This defeats the point of having a piece of art however as you would rather display it than have it placed somewhere out of sight.

Hopefully now you at least understand some of the basics of what lightfastness means and how it can affect your work as both a professional artist or a hobby artist.

As long as you maintain good practice, focus on the colours you’re using and how lightfast they are individually and protect your art in the best way possible once it’s completed you should be fine.

Christopher Durant is a professional coloured pencil artist from South Yorkshire. He sells his prints and original artwork online. You can keep up to date with the latest updates from Christopher through his Facebook page.

1 Response

  1. What an excellent article! About the only thing I knew about lightfastness was that red fades quickly, don’t hang pictures in bright light. I learned a lot today. I was particularly interested in how manufacturers code their lightfastness in the various mediums, colored pencils in particular.

    Thank you, Christopher, can’t wait to read your next article!

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